Regional Myocardial Tissue Characterization by Cardiac Magnetic Resonance Is Associated With Heart Failure Development in Asymptomatic Transthyretin Amyloid Cardiomyopathy.

Background: Because the number of asymptomatic individuals diagnosed with transthyretin amyloid cardiomyopathy (ATTR-CM) has been rising, it is important to identify myocardial tissue characteristics associated with heart failure (HF) development in asymptomatic patients with ATTR-CM. Methods and Results: Among 113 patients with ATTR-CM, 14 were asymptomatic (mean age 75±6 years; 79% male) and underwent echocardiography and cardiac magnetic resonance imaging (CMR). Over a median follow-up of 770 days, 6 patients developed HF. Compared with those who remained asymptomatic, these patients had a higher left ventricular mass index (LVMI) on echocardiography (P=0.020). On CMR, native T1 was significantly higher at the basal inferior (P=0.0277) and inferolateral (P=0.0017) segments, whereas the extracellular volume (ECV) fraction was significantly higher at the basal inferolateral (P=0.0296) and anterolateral (P=0.0092) segments. LVMI correlated with native T1 (r=0.599, P=0.024) and ECV at the basal inferolateral (r=0.780, P<0.001) and anterolateral (r=0.624, P=0.017) segments. Kaplan-Meier analysis showed that patients with higher LVMI, native T1 at the basal inferolateral segment, and ECV at the basal anterolateral segment had a higher incidence of HF development. Conclusions: In asymptomatic ATTR-CM patients, HF development was associated with increased LVMI and regional myocardial tissue abnormalities in the basal lateral wall detected by native T1 and ECV on CMR; however, these findings should be considered exploratory and require validation in larger studies.